The low calorie diet is tried and true, and it's been around since the beginning. A low calorie diet is one that consists of 1500 to 1800 calories. On the other hand, a very low calorie diet (VLCD) is one that is 800 calories or less. For a VLCD, it is recommended that it is undertaken with a doctor's supervision.
Does It Work?
The low calorie diet almost always works. The basic rule of losing weight is that you must take in fewer calories than you use. If you take in around 1500 calories per day, you will almost surely lose weight. One thing to note is that if you restrict your calories too much, your metabolism will slow down, which will actually slow down weight loss. The trick is to lower your caloric just enough to maintain your metabolism but to eat a bit less than you burn off.
Is It Safe?
A low calorie diet can be quite safe, providing that you choose a variety of foods and that you are getting the vitamins and nutrients that you need. Following a very low calorie diet where you are only consuming 800 calories or less, you may not be able to get enough nutrients. For this reason, you may be required to take a multivitamin along with medical supervision. A VLCD should only be used for the short-term.
What Should You Eat?
There are no specific foods to eat on the low calorie diet; however, in order to have a balanced diet while keeping within the caloric guidelines of 1500 to 1800 calories, you will have to choose your meals carefully. For example, if you decide to have a fast food milkshake, you will be spending about 300 of your calories. As with any good diet, getting enough vitamins, nutrients and fiber will require you to fruits, vegetables, and fiber at the very least.
Certainly, if all you ate each day was 5 milkshakes, you might actually lose weight, but you would not be eating in a healthy way.
Choose a variety of foods, including fruits, vegetables, lean meats and low-fat or nonfat dairy, beans, legumes, nuts and seeds.
The best bet is to find menus that you feel comfortable with. If the diet is too hard to follow, it won't stick and you won't achieve your goals. The easier a diet is to implement, the easier it will be to maintain.